More live performers are turning to capacitor microphones because of their ability to deliver a more detailed sound with extended high end. To meet this demand, Shure have produced the KSM9 live performance vocal mic.

Paul White

The KSM9 employs a back-electret capacitor capsule, tuned to avoid peaks in the frequency response that might provoke the early onset of acoustic feedback. Utilising a dual gold-on-Mylar diaphragm system, the capsule is also engineered to produce less of a proximity effect than typical cardioid-pattern vocal microphones, making the mic-to-mouth distance a little less critical. Some proximity effect remains (you can't buck the laws of physics) and indeed is desirable, as it allows the singer to 'work' the microphone, but it doesn't get overly bass-heavy when your lips are virtually touching the grille.

Polar patterns

The capsule is suspended in a resilient shockmount to minimise handling noise.

The capsule is suspended in a resilient shockmount to minimise handling noise.

Both wired and wireless options are available (the review model is wired), and there's a choice of metallic champagne or charcoal grey finish. If you're wondering why the capsule utilises two diaphragms, it is to enable the KSM9 to be switched between two polar patterns — cardioid and supercardioid. Supercardioid produces a tighter pattern than a regular cardioid, which can be useful in cutting down spill from other performers, but when positioning stage monitors it is essential to take account of the pattern you are using.

The cardioid pattern has its 'deaf' spot directly behind the microphone, so you should try to aim the back of the mic body directly down towards the monitor to minimise feedback problems. By contrast, the supercardioid is least sensitive around 45 degrees off its rear axis, so you need to aim the monitors accordingly. Also, be aware that though the supercardioid pattern offers the best rejection of off-axis sounds originating elsewhere on the stage, it is also the least forgiving if the singer isn't great at controlling their position relative to the mic, which may in turn lead to obvious level changes during performance if the pattern is too tight. Fortunately the KSM9 is still pretty friendly in supercardioid mode, so the designers have clearly taken this into account.

Phantom power

Being a capacitor microphone, the KSM9 needs phantom power to operate, though this can be in the range of 11V to 52V, so those budget mixers that deliver lower than the standard 48V supply should still power it adequately. The back-electret capsule itself is permanently charged, so its performance is unaffected by changes in the phantom power voltage, but the preamp headroom (the level it can accept before distorting) will be reduced slightly at lower voltages. Normally, the mic can handle in excess of 150dB before clipping, which is immensely loud.

Construction

Outwardly, the mic looks and feels pretty conventional, and weighs about the same as an SM58 (300g), so it feels 'right' in the hand. The basket diameter is a little under two inches, while the body length is 7.5 inches. Unscrewing the basket reveals it to be made up of two layers of tough steel wire, with an inner foam sleeve that can be removed for washing in mouthwash or TCP to keep it bug free. Another fine perforated screen sits over the end of the capsule, which is itself suspended in a resilient shockmount to minimise handling noise.

Below the shockmount is a small horizontal toggle switch to select between cardioid and supercardioid. This seems quite a practical system, as if you have to take the basket off to change patterns, you're unlikely to change it by accident, though it would have been nice to have some external visual confirmation of which pattern the mic is set to with the basket in place, especially if you use more than one KSM9 with some set to cardioid and others to supercardioid.

Output

The onboard preamp is pretty standard for this type of mic, in that it features Class-A electronics with an FET front end and a balanced, transformerless output stage. What this adds up to is an electronically quiet microphone (the self-noise of 22dB is negligible for a mic designed for close-up use, even though it would be nothing special in a studio mic) with a useful frequency response extending from 50Hz to 20kHz. There is, however, a built-in low-frequency roll-off to balance the proximity effect, so that the low end doesn't get overbearing when the mic is used up close. There's also a presence peak giving the sound a few dBs of lift above 3kHz, but this is gentle enough to avoid harshness and adds a welcome airiness to the sound, as well as helping it cut through a busy backline. With a sensitivity of -51 dBV/Pa at 1kHz, the output you get is in the same ballpark as for a dynamic mic, such as an SM58, which makes sense in situations where you're working with both types of microphone.

Performance

In comparison with some less costly, back-electret, live vocal mics I had to hand for test purposes, the KSM9 consistently delivered the smoothest and most musical result, though the slightly more brash upper mid-range on the cheaper models might actually help some performers cut through better. The impression is of a studio-quality mic designed for live performance, which is clearly what Shure were aiming for in this case, and the sound is essentially the same in both cardioid and supercardioid modes, with a nice breathy high end. Handling noise is impressively low, and the resistance to popping is as good as I've heard from this type of microphone. By way of output, the levels of the KSM9 and my test mics were pretty evenly matched, and rejection of feedback was nominally similar too.

In my experience, it is generally more difficult to choose a good-sounding mic for female vocalists than male vocalists, and that's where the KSM9's smooth, but open high end might win the day. It also makes a great male vocal mic, but at the asking price you need to be very certain it is the right model for you and there are several factors to consider. The Rode M3 we reviewed recently is about a fifth of the price and sounds similarly studio-like, but it isn't nearly as good at rejecting popping. The LD 1011, which comes in at about a tenth of the price, is also good on the popping and handling noise front, but it doesn't sound quite so smooth and natural. Nevertheless, its slightly more brash presence character may help some vocalists who need intelligibility more than they need silky smoothness.

Conclusion

Judged on a combination of sound, resistance to feedback and popping, and build quality, the KSM9 is the best live vocal capacitor microphone I've had the pleasure of using to date, but there are viable alternatives snapping at its heels for considerably less money, and unless you have a very high-quality sound system, you may not hear a great deal of difference. However, for the professional performer who simply must have the best, the KSM9 ticks all the right boxes.